A strange sound _____ yesterday evening. [ ]
A. was heard
B. hears
C. heard
D. is heard
答案:A
. If I had got back 5 minutes earlier, I _________ him.
A.would see
B.would have seen
C.will have seen
D.had seen
在钻孔和灌注混凝土过程中都容易出现的事故是()
A.坍孔
B.钻孔漏浆
C.扩孔
D.断桩